Linux: Use After Free
CVE-2026-23191 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.0 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions f57467114f40c5aacebbea96fb4ff9e5cd2b7f18, c99be0d5af02adebe9cb6f9869d20397fa9935a3, f3ce8be893726899e3053cf8059ecc95d8410359 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to f57467114f40c5aacebbea96fb4ff9e5cd2b7f18 or c99be0d5af02adebe9cb6f9869d20397fa9935a3 or f3ce8be893726899e3053cf8059ecc95d8410359 or 0e6245b2424d126ac90018142d09f0707e12998b, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.70 or 6.18.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, f57467114f40c5aacebbea96fb4ff9e5cd2b7f18; b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, c99be0d5af02adebe9cb6f9869d20397fa9935a3; b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, f3ce8be893726899e3053cf8059ecc95d8410359; b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, 0e6245b2424d126ac90018142d09f0707e12998b; b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, bad15420050db1803767e58756114800cce91ea4; b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, 5727ccf9d19ca414cb76d9b647883822e2789c2e; b1c73fc8e697eb73e23603e465e9af2711ed4183 up to, but not including, 826af7fa62e347464b1b4e0ba2fe19a92438084f; 2.6.37 | f57467114f40c5aacebbea96fb4ff9e5cd2b7f18, c99be0d5af02adebe9cb6f9869d20397fa9935a3, f3ce8be893726899e3053cf8059ecc95d8410359, 0e6245b2424d126ac90018142d09f0707e12998b, bad15420050db1803767e58756114800cce91ea4, 5727ccf9d19ca414cb76d9b647883822e2789c2e |
| Linux | Linux Kernel | 2.6.37 up to, but not including, 6.12.70; 6.13 up to, but not including, 6.18.10; 6.19 | 6.12.70, 6.18.10 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.0 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ALSA: aloop: Fix racy access at PCM trigger The PCM trigger callback of aloop driver tries to check the PCM state and stop the stream of the tied substream in the corresponding cable. Since both check and stop operations are performed outside the cable lock, this may result in UAF when a program attempts to trigger frequently while opening/closing the tied stream, as spotted by fuzzers. For addressing the UAF, this patch changes two things: - It covers the most of code in loopback_check_format() with cable->lock spinlock, and add the proper NULL checks. This avoids already some racy accesses. - In addition, now we try to check the state of the capture PCM stream that may be stopped in this function, which was the major pain point leading to UAF.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Use After Free vulnerabilities
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- 7.8 High severity
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